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Suji: Difference between revisions
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==Basic Theory== | ==Basic Theory== | ||
In short: | In short: a tile becomes safer against an opponent if they've discarded every tile (of the same suit) that is an interval of 3 from that tile. For example, if an opponent had discarded a 4, then both 1 and 7 of the same suit are safer. If an opponent discarded both 1 and 7, then the 4 becomes safer. (If an opponent had only discarded a 1, the 4 is not much safer.) | ||
The explanation is as follows: | |||
*The most common type of wait is an [[ryanmen|open]] [[wait]] (i.e. a [[ryanmen]] wait). An open wait is a wait that wins off two sides of a sequence, e.g. a hand containing {23}, or a hand containing {34}. | *The most common type of wait is an [[ryanmen|open]] [[wait]] (i.e. a [[ryanmen]] wait). An open wait is a wait that wins off two sides of a sequence, e.g. a hand containing {23}, or a hand containing {34}. | ||
*[[Shuntsu|Sequences]] are comprised of three sequential tiles. Therefore, an open wait will win off two tiles that are 3-apart. For example, {23} can win off either a 1 or 4 of the same suit. {34} can win off 2 or 5 of the same suit. This continues until you get the intervals of: 1-4, 4-7, 2-5, 2-8, 3-6, and 3-9. | *[[Shuntsu|Sequences]] are comprised of three sequential tiles. Therefore, an open wait will win off two tiles that are 3-apart. For example, a {23} ryanmen can win off either a 1 or 4 of the same suit. {34} can win off 2 or 5 of the same suit. This continues until you get the intervals of: 1-4, 4-7, 2-5, 2-8, 3-6, and 3-9. | ||
*Due to the [[furiten]] rule, if a player has previously discarded any tile they could have won off of, they cannot win from other players. | *Due to the [[furiten]] rule, if a player has previously discarded any tile they could have won off of, they cannot win from other players. | ||
*Therefore, if | *Therefore, if every tile in a suji interval is discarded, then other tiles in that interval become safer against that player. | ||
** | **If an opponent discards a 4, it is ''impossible'' for an opponent to have an open wait on 1 (without being in furiten). There is only one interval for the 1, that being 1-4, which is eliminated. Therefore, the 1 is safer against that opponent. Likewise, the 7 becomes safer when a 4 is discarded, due to the 4-7 interval being impossible. | ||
**If an opponent discards a 1, it is not impossible for an opponent to have an open wait on 4. There are two different intervals for 4: 1-4 and 4-7. After discarding a 1, an opponent could still have an open wait on 4-7 interval. In order for the 4 to be a "full" suji, both 1 and 7 have to be discarded. The same logic applies to tiles numbered 5 and 6. | |||
Note: suji also applies to the other forms of furiten. So long as a given tile is 100% safe ([[genbutsu]]) against an opponent, you can use the suji of that tile. After an opponent declares [[riichi]], then any non-winning tile discarded by anyone becomes safe through furiten. Therefore, suji can be applied to those discarded tiles as well. So if an opponent declares riichi, and the next opponent discards a 4, then 1 and 7 are still considered suji. | Note: suji also applies to the other forms of furiten. So long as a given tile is 100% safe ([[genbutsu]]) against an opponent, you can use the suji of that tile. After an opponent declares [[riichi]], then any non-winning tile discarded by anyone becomes safe through furiten. Therefore, suji can be applied to those discarded tiles as well. So if an opponent declares riichi, and the next opponent discards a 4, then 1 and 7 are still considered suji. | ||
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The strategy of suji may be used offensively. By utilizing suji in reverse, a player may use a tile within an interval to lure out a winning tile along the same interval. A defending player may presume a certain tile to be safe by suji, when it is actually not. This is commonly known as the "suji trap". | The strategy of suji may be used offensively. By utilizing suji in reverse, a player may use a tile within an interval to lure out a winning tile along the same interval. A defending player may presume a certain tile to be safe by suji, when it is actually not. This is commonly known as the "suji trap". | ||
A common way for this to occur is when a player has a ryankan shape, such as 468. In this case, the opponent can discard the 4, and wait on 7. This takes advantage of other player's knowledge of suji. | A common way for this to occur is when a player has a ryankan shape, such as 468. In this case, when reaching tenpai with a ryankan, the opponent can discard the 4, and wait on 7. This takes advantage of other player's knowledge of suji. | ||
== Other suji == | == Other suji == | ||
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In addition, ura suji theory assumes your opponent is going for maximum [[tile efficiency]]. | In addition, ura suji theory assumes your opponent is going for maximum [[tile efficiency]]. | ||
The reason ura suji is not that much more dangerous than normal is because it assumes a (35) kanchan had existed in the first place. The 5-pin could have been an unrelated tile, or it could have been part of a 57 kanchan, or part of a completed 556 shape, or part of a completed 135 shape, etc. Even if the kanchan did exist, an opponent could have | The reason ura suji is not that much more dangerous than normal is because it assumes a (35) kanchan had existed in the first place. The 5-pin could have been an unrelated tile, or it could have been part of a 57 kanchan, or part of a completed 556 shape, or part of a completed 135 shape, etc. Even if the kanchan did exist, an opponent could have completed the 23 sequence before reaching tenpai. | ||
== References == | == References == | ||